Process of peroxidizing storage-battery plates.



UNITED STATES PATENT OFFICE.

RUFUS N. CHAMBERLAIN, OF DEPEW, NEW YbRK, ASSIGNOR To THE GOULD STORAGEBATTERY COMPANY, OF NEW YORK, N. Y., A CORPORATION OF WEST VIRGINIA.

PROCESS OF PEROXIDIZING STORAGE-BATTERY PLATES.

SPECIFIOATIONfOrming part of Letters Patent No. 712,995, dated November4, 1902.

Application filed August 23, 1900. Renewed September 10, 1902. SerialNo. 122,801. (No specimens.)

Too/ll whom it may concern.-

Be it known that I, RUFUS N. CHAMBER- LAIN, a citizen of theUnitedStates, residing in Depew, in the county of Erie and State of NewYork, have invented certain new and useful Improvements in Peroxidizin gStorage- Battery Plates, of which the following is a 1 specification.

- This invention relates to improvements in peroxidizing storage-batteryplates.

It has been proposed to use in peroxidizing lead plates 2. solutioncontaining sulfuric acid, to which is added a certain proportion ofalkaline nitrates, resulting in a bath containing sulfuric acid,with asmall percentage of nitric acid. This process has the disadvantage ofleaving a certain amount of soluble alkaline sulfates in the bath, whichmay lead to injurious secondary reactions. It has 2o also been proposedto add a small proportion of nitric acid direct to the bath; but in thiscase the disadvantage exists that the nitric acid not being set free ina nascent state in the bath is not as energetic as it would be if itwere nascent.

The object of my invention is to present the nitric acid to the plate ina more efiective manner, and to this end I add to the sulfuricacidsolution a suitable proportion of nitrate c of, a metal whose sulfate issubstantially insoluble in the bath producedfor example, nitrate oflead. As a result, thesulfate is immediately removed from the bath, andthe reaction proceeds in the most efficient man- 3 5 nor withoutsecondary reactions. The nitric acid is liberated whether wholly by thedirect chemical action or partly by such action and partly byelectrolytic effect in a nascent state in the bath itself, and itsperoxidizing 4o effect is correspondingly increased. I may and prefer touse for the supply of nitrate of lead the icy-product of a previousstage of the plate-treating processnamely, the nitrate-of-lead solutionresulting from the pickling operation. In case the nitrate-of-leadsolution so produced is not strong enough to use directly it may be madesufficiently strong either by concentration or by addition of lead or ofsolid lead nitrate. The precipitate also from the peroxidizingbathnamely, lead sul- 5o fatemay be recovered and utilized, for example,by reduction or fusion into metallic lead for grids or otherwise.

The process is preferably carried on as follows: The plates are firstplaced in a pickling bath composed of dilute nitric acid and are thereinpickled by the action of said acid, assisted by an electric current, thenitric acid being replenished from time to time, so as to maintain anefiective solution, while the nitrate of lead is gradually accumulatedin the bath, and eventually the solution becomes so charged therewith asto be serviceable in the following operation, an additional amount oflead or leadv nitrate being supplied to such solution, if necessary. Theplates are then peroxidized in a bath prepared as follows: To a solutionof sulfuric acid containing 36.7 parts of H to one hundred parts ofwater are added sixteen parts of nitrate of lead, or if the nitrate oflead is added in dissolved state, as in the form of solution from thepickling-bath, then the amount of water in the original sulfuric-acidsolution is 'correspondingly decreased, so that the propor- 75 tions ofwater, sulfuric acid, and nitrate of lead remain substantially as. abovestated. The chemically cleaned or pickled plates are placed in thisbath, preferably before the addition of the nitrate of lead, so that onsuch addition nitric acid is liberated in a nascent state and a powerfuloxidizing bath is produced. At the same time the plate is connected withsuitable electrodes and electric energizing connections, the plate to beperoxidized being arranged as the anode. Upon passage of the electriccurrent the nitric acid, which is set free by the chemical andelectrolytic actions, is caused by the electric current to attack thesurface of the anode, forming nitrate of lead, which is immediatelyconverted by the sulfuric acid present into sulfate of lead, and as thisefiect takes place in direct contact with the lead plate the sulfate oflead adheres to the lead plate or grid. 9 5 This sulfate of lead isgradually converted into peroxid of lead by the oxygen which isliberated at the anode through the electrolysis of the water and thedecomposition of the nitric acid, the oxidizing effect being increasedby the nascent character of the nitric acid. As many plates may betreated in the bath as may be found desirable, nitrate of lead beingadded from time to time to maintain the efficiency of the bath, and theprecipitate-namely,sulfate ofleadwhich gradually accumulates in the bathmay be removed from time to time and utilized by reduction to metalliclead or otherwise. After theplates have thus been provided with asufiicient coating of peroxid they are removed from the above-describedbath, washed, and placed in the ordinary forming solution and. are thereelectrolyzed sufficiently to effectually clear them of any slight amountof sulfate which remains therein, although the same eifect may beproduced in the peroxidpickling operationnamely, nit-rate of leadisutilized in the peroxidizingoperation,while the byproduct of the latteroperation namely, lead sulfate-is also utilized.

Vhat I claim as new, and desire to secure by Letters Patent, is-

l. The process of treating storage-battery plates which consists insubjecting the plates as anodes to electrolysis in a bath consisting ofa solution of sulfuric acid to which nitrate of lead is added.

2. The process of treating lead plates for storage batteries whichconsists in pickling the lead plates in a dilute nitric-acid solutionand thereafter subjecting the lead plates as anodes to electrolysis in abath consisting of a solution of sulfuric acid to which the nitrate oflead resulting from the pickling operation is added.

3. The process of treating lead plates for storage batteries whichconsists in subjecting the plates as anodes to electrolysis in a bathconsisting of a solution of sulfuric acid to which nitrate of lead isadded and removing from such solution the resulting precipitate ofsulfate of lead.

4. The process of peroxidizing lead plates for storage batteries whichconsists in subjecting the plates as anodes to electrolysis in a bathconsisting of a solution of sulfuric acid to which is added the nitrateof a metal whose sulfate is substantially insoluble in the bath, therebysetting free nascent nitric acid and at the same time precipitating theresulting sulfate.

RUFUS N. CHAMBERLAIN. Witnesses:

A. P. KNIGHT, W. P. HAMMOND.

